DE1904844A1 - Hydraulic braking system - Google Patents

Description

The invention relates to a hydraulic brake system with a memory as a pressure medium, in particular for power-operated brakes.

It is common practice to provide towing vehicles with hydraulic devices that are operated by means of valves of the type with so-called "open middle position" or "open neutral" · · steep "can be controlled. Normally, the pump to supply these" devices is a pump with a constant flow rate, e.g. a gear pump. The control valves mentioned are connected in series, εο that when the valves are not actuated, the Liquid delivered by the pump flows through the valves in sequence and flows back again, so that the pump works without pressure. As soon as one of the control valves is actuated, the return flow is interrupted or throttled, so that the pump can build up a pressure which, via the actuated control valve, is transmitted to the relevant hydraulic device, e.g. a hydraulic cylinder.

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The invention is based on the object of filling a hydraulic accumulator of a brake system of the type mentioned above with pressure medium by means of a pump for a hydraulic system in which valves with "open center position" or "open neutral position * ^{1 are provided.}

To solve this problem, a relief valve is provided according to the invention, via which the memory by means of a hydraulic pump, in particular a pump constant flow rate, can be filled to a predetermined pressure and via which the puropen line can be freely connected to the reflux, so that the pump works without counter pressure, when the predetermined pressure is reached. The relief valve is thus int with the control valves for the hydraulic devices connected in series.

Advantageously, the relief valve opens to the return flow at a higher pressure ala that at which it is to Reflux closes.

In a preferred embodiment of the invention it is provided that the relief valve comprises a valve closing body which is movable against a valve spring in order to open a valve seat between an inlet chamber communicating with the inlet opening and an outlet chamber communicating with the return opening, and that d The valve sealing body is attached to a piston of a larger diameter than the valve seat, the piston being exposed to the pressure in the inlet chamber with one end and the other end of the bridge in a bridge catalyst, which is connected to the bridge opening _s old which is the opening of the inheritance via a liückßoiilagventil veröira & em «,

The invention and advantageous details of the invention are explained in more detail below with reference to schematic drawings of several exemplary embodiments.

Pig. 1 shows that part of the vehicle brake system

according to the invention, which is arranged on a towing vehicle,

Fig. 2 shows that part of the brake system on a trailer to be attached to the towing vehicle is arranged,

Pig. 3 and 4 show in representations as in Pig. 1 and a second embodiment of a vehicle brake system according to the invention,

Pig. 5 shows the scheme of that part of a third

Implementation of a vehicle brake system according to the invention, which is arranged on a towing vehicle and

Pig «6 shows that part of a vehicle brake system

according to Pig. 5 »which is arranged on a trailer to be attached to the towing vehicle.

1 and 2 is a hydraulic brake system for a trailer fed by a hydraulic pump 10, the is arranged on a towing vehicle to which the trailer is to be attached. The pump 10 supplies the hydraulic ones Equipment of the towing vehicle with hydraulic pressure medium and works with constant delivery rate. An example in Fig. 1 shown single-acting hydraulic cylinder 11 is fed by a control valve 12 with two / one positions, which has an "open neutral position", i.e. that in its neutral position that via a line 13 by means of the pump feeds pressure medium supplied to its inlet into a line 14. In practice, a number of hydraulic in-

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directions on the towing vehicle provided in most cases Double-acting devices - controlled by three-position, "open-center" valves. · Me valves are connected in series so that when a valve is in its "open center position" or in its "open neutral position" is located, from the pump 10 pumped pressure medium is fed to the next valve in the series. In other words: Line 14 is connected to the inlet of the next valve in series, rather than from the hydraulic devices lead away. Therefore, when all valves are in their "open center position" or "open neutral position", the pump feeds the pressure medium directly into the line 14, through which it is returned to a container 15, from which the pump hydraulic Sucks pressure medium through a line 16. If one of the valves away. the valve 12 is actuated, the pressure medium returned through the line 14 is throttled by one Build up pressure in line 13. The pressure medium supplied by the pump 10 becomes the hydraulic one with this controlled pressure Cylinder 11 supplied. The cylinder 11 is connected via the valve 12 to a return line 17 which leads to the Container 15 leads when valve 12 is in its neutral position shown. The hydraulic system for the hydraulic The device of the towing vehicle is basically a system with constant volume in which the pressure is changed according to the requirements of the hydraulic devices. However, it is necessary to operate the trailer brakes a pressure medium source is required, which supplies pressure medium at constant pressure. This source is provided by the pump 10 and a relief valve 18, the inlet opening 19 of which is connected to the line 14.

The trailer brake system shown in Fig. 2 comprises one hydraulic accumulator 170 and at least one hydraulic actuating device, two such actuators

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gen in Pig. 2 are shown. The pistons 23 of the actuators "operate the brake shoes or brake pads, including" at In the embodiment shown, a jib arrangement 24 is provided is. This part of the braking system arranged on the trailer is connected to the part of the arranged on the towing vehicle Braking system by means of a double-wire, self-sealing Quick release breakaway coupling 25 (Pig. 1) connected. An accumulator line 26 (Fig. 1 and 2) leads from a trailer coupling head 27 to the memory 170, while a brake line leads from a second trailer coupling head 29 to the hydraulic actuating devices 21 and 22.

The hydraulic accumulator 170 is a multipurpose accumulator insofar as al? it not only forms a source for the pressure medium that actuates the trailer brakes, but also serves to mechanically actuate the trailer brakes when the pressure in the pressure medium in the memory drops. The memory 170 comprises a stationary body 171, in one end of which a piston 172 slides. The rod 32 of the piston 172 is connected via a connecting rod 33 to a yoke 34, the ends of which are connected to the piston 23 of the hydraulic actuating devices 21 and 22 by means of brake wires 35. A peder 36 acts between the body 171 and a sleeve 37 ' which, at one end, has a puddle against which a collar 173 of the piston 172 rests. The peder 36 thus pushes the piston 172 into Pig. 2 to the left to apply the trailer brakes mechanically. The peder has enough tension; to fully apply the trailer brakes. A handbrake lever 38 engages the connecting rod 33 to be able to actuate the trailer brakes independently of the Peder 36th For this purpose, a backlash connection 39 is provided between the connecting rod 33 and the piston rod 32. The body 171 includes a cylindrical cavity 174 supported by a floating piston 177

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is divided into chambers 175 and 176 »Chamber T75 serves sum Storage of hydraulic fluid under pressure and is in communication with conduit 26 through a bore 178 in piston 172. The chamber 176 is via a not shown The inlet is filled with a gas under suitable pressure to create a gas cushion. Instead of the gas cushion For example, a compression spring can be provided to act between the piston 177 and the left end of the body 171.

The chamber 175 is filled with hydraulic fluid via a relief valve 18 and a line 4-4 (Fig. 1), which leads from a pressure outlet opening 45 of the relief valve 18 su the towing vehicle coupling head 46, which with the trailer coupling head 27 is coupled. The relief valve has a discharge opening 47 which is connected to the container via a line 48 communicates. The relief valve comprises a conical closing body 49 which by means of a spring 50 against a Valve seat 51 is biased. The closing body 49 is attached to a piston 52, which is a slightly larger Diameter than the valve seat 51 has. The valve inlet chamber 53 at the left end of the piston 52 is via a passage 54 with the inlet port 19 in communication. This is about a

opening

Check valve 55 connected to outlet 45. A pressure chamber 56 on the right side of the piston 52 is also with the outlet port 45 in communication. The valve karamer 57, which serves as an outlet chamber and receives the spring 50, is with a discharge port 47 is connected. The relief valve 18 enables the pump 10, for example a gear pump and normally delivers a constant flow rate at a variable flow pressure, the chamber 175 of the accumulator fills up with hydraulic fluid to a predetermined pressure.

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When the pump 10 starts to operate and the hydraulic Vorrichtungen.des towing vehicle operates .DH _v when all the valves are in their open center or neutral position, the delivered by the pump liquid flows through the lines 13 and 14 to the inlet opening 19 of the Valve 18. First, the spring 50 holds the closing body 59 on its seat 51 so that the liquid flows through the check valve 55 to the outlet opening 45 and from there through the storage lines 44 and 26 to the chamber 175 of the storage. The memory is shown filled in FIG. 2. Initially, however, the piston 172 is in its left limit position and the piston 177 is in its right limit position, in which it rests against the stop 179 of the chamber 175. When the compressive force acting on the piston 172 becomes as great as the biasing force of the spring 36, the. Piston 172 moves to the right, thereby releasing the trailer lawn from the mechanically applied actuating forces. When the pressure of the liquid exceeds that which the gas cushion in chamber 176 initially has, piston 177 moves to the left until the pressures in chambers 175 and 176 are equalized.

While the check valve 55 is open and the ^storage: is filled rather 177 with liquid, keeping the forces of the spring 50 and the pressure forces within the valve chamber 53, the difference of the surfaces of the piston 52 and the valve seat 51 to be effective in accordance with the closing body 49 against its seat 51 against the force of the accumulator pressure which acts on the piston 52 in the chamber 56, closed. When the accumulator pressure reaches a value predetermined with the characteristics of the spring 50 and the pressure in the chamber 53, the closing body 49 is moved to the left, v / o by opening the valve to open the inlet port 19 with the discharge port 47 in

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Bring connection that is under container pressure. Once the valve is slightly removed from its seat, the further opening movement takes place very quickly, since the pressure in the valve inlet chamber 53 drops, the check valve 55, however, keeps the pressure in the chamber 56 at the accumulator pressure. When the valve is fully open, the Pressure in chamber 56 acting on piston 52 is the force the spring 50 is completely overcome. The valve closing body 49 can only close again when the pressure in the chamber 175 of the memory has dropped to a smaller value, with which it no longer applies the force of the spring 50 on the piston 52 can keep balance. While the closing body 49 is held in its illustrated fully open position by the pressure in the storage chamber 175, is that of the Line 14 leading to hydraulic devices of the towing vehicle freely with container 15 via relief valve 18 and the discharge line 48 so that the hydraulic devices of the towing vehicle operate in the normal manner can. The check valve 55 prevents the accumulator pressure from acting back on these hydraulic devices.

A metering valve 160 (Pig. 1) is arranged on the towing vehicle to hydraulically actuate the trailer brakes. The metering valve 160 has an inlet opening 161 which is connected to the storage line 44 via a branch 62, an outlet opening 63 which, via a line 64, is connected to a towing vehicle coupling head 65, which is connected to a trailer coupling head 29 is coupled, and a discharge opening 66, which is connected to the container 15 via a line 67 is. The metering valve 160 also has a control opening 68, which is connected to the master brake cylinder (not shown) via a line 69. of the towing vehicle is in connection.

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Das.Zumeßventil 160 comprises a housing 70 with a remote Drilling. A portion 71 of this bore receives a piston 72, the left end of which is in one with the control port 68 related control caramers 73 protrudes. The piston 72 is supported on a second piston 74, which is in a Bore section 75 of slightly larger diameter than section 71 slides. The right end face of the piston 74 is limited a Bremsdruckkaramer 76, which is connected to the outlet opening related A rod 77 on the piston 74 extends passes through the pressure chamber 76 and is in a smaller diameter portion 78 of the stepped Drilled hole. The right end of the bore section 78 v / eist a first valve seat 79, while the mouth a longitudinal channel 80 in the rod 77 at the free end of this rod forms a second valve seat 81. A conical valve closing body 82 works together with both valve seats 79 and 81. The Schli'e'ßkörper 82 has a rod 83, the extends through a larger diameter portion 84 of the stepped bead and forms a seal is guided in a section 85 with a reduced diameter of this bore. The valve plug rod 83 82 has a longitudinal channel 86 which leads from a chamber 87 at the right end of the stepped bore to inclined channels in the Closing body 82 leads. These inclined channels open into the conical surface of the valve closing body 82 so that they at in each position of the piston 74 and the closing body 82 are in communication with the pressure chamber 76, i.e. the orifices lie on a diameter which lies between the diameters of the valve seats 79 and 81. The bore sections 78 and 35 hrben the same diameter, so that the valve closing body 82 is hydrostatically balanced. The larger diameter bore portion 84 forms a valve

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tilkammer 88, the rait the inlet port 61 in connection stands. The longitudinal channel 80 in the piston rod. 77 is connected to an annular groove 90 in the piston 74 via transverse bores. A channel 91, which leads to the discharge opening, opens into this annular groove 90 66 leads at least when the valve seat 81 from the valve closing body 82 is removed, as shown in FIG. 1 is shown.

When the brakes of the towing vehicle are not applied, the master cylinder does not develop any pressure, so that in there is no pressure in the control chamber 73. The pistons 72 and 74 are therefore supported by a spring 92 which is located in the pressure chamber 76 is included, biased in its left position (see I'ig. 1). The closing body 82 is supported by a closing spring 93, which is received in the valve chamber 88, pressed against the seat 79. This situation is illustrated in Figure 1 and it is it can be seen that the valve seat 81 is removed from the base body 82 when the piston 74 is in its left end position is located, whereby the pressure chamber 76 via the channel 80 with the annular groove 90 and thereby via the channel 91 with the discharge opening 66 is connected, which leads to the container 15 via the line 67. The hydraulic actuators 21 and 22 are therefore not pressurized when the control chamber 73 is not under pressure.

When the tractor brakes are applied, the Pressure in the master cylinder via line 69 to the control chamber

73 transmitted and acts on the piston 72. As the pressure chamber 76 is under container pressure (usually atmospheric or other low pressure), pistons 72 and are grounded

74 against the Krafi; dor spring 92 pressed to the right. If the Valve seat 81 touches the base body 32, the pressure chamber 76 is separated from the discharge opening 66. Further movement the piston 72 and 74 to the right lifts the closing body 82. from the valve seat 79, whereby the valve inlet chamber 88 with

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the pressure chamber 76 is connected. The cooperating with the seat 79 Shooting body 82 controls the flow, the pressure 7 liquid from the storage chamber 175 (Fig. 2) via the lines 26, 44, 62, 64 and 28 to the hydraulic actuators 21 and 22. When the pressure in the pressure chamber 76 increases and approaches the pressure in the control chamber 73, the pistons 74 and 72 are moved slightly to the left again, in order to substantially prevent a flow between the valve closing body 82 and the valve seat 79. Because the closing body 82 is hydrostatically balanced, the pressure in the pressure chamber 76 through the metering valve is proportional to the Pressure in the control chamber 73 is controlled. As a result, the pressure in the hydraulic actuation device 21 and 22 is immediate proportional to the pressure generated by the master cylinder. Since the piston 74 has a slightly larger diameter than the Piston 72, the pressure in chamber 76 is only slightly lower than the pressure in chamber 73. keep. If desired, the piston 74 can also have a slightly smaller diameter than the piston 72 or both pistons can have the same diameter. Furthermore, the pistons 72 and 74 can be in one piece. When the brake is released, the pressure in the control chamber 73 drops and the spring 92 pushes the pistons 74 and 72 into their left Endatellungen in which the pressure chamber 76 with the container 15 connected, whereby the hydraulic actuators relieved of pressure v / earth "

If the towing vehicle can only be operated mechanically Brakes and no master cylinder, a loading element can be in be arranged on one of the links of the towing vehicle brakes. The loading moment k: -nn be a hydraulic L-irieelemcnt that with the control camera 73 is in communication. The charging element can alternatively trigger an electrical signal and to this

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Purpose of having an electrical strain transducer, which is switched into an electrical.circuit, in, .the one in its .. Size of the applied braking force proportional electrical signal is generated. In this case the metering valve is 160 designed as a solenoid valve, which is in the electrical circuit. is switched on to receive this signal and the Adjust the pressure in the brake pressure chamber proportional to the signal.

When so much pressure fluid is from the storage chamber 175 (Pig. 2) has leaked that the pressure in the chamber 56 (Fig. 1) has dropped to a value at which the spring 50 can close the closing body 49 of the relief valve 18, the memory 170 is replenished by the pump 10 in the manner described above. Formally, this is lower Pressure is still higher than the lowest pressure at which the piston 177 is pushed away from the stop 179, and the As shown, spring 36 is fully compressed, wherein the flange 94 of the piston 172 abuts the housing part 171, so that the trailer brakes completely from the mechanical applied actuating force are relieved. However, if the pressure in the hydraulic accumulator is significantly below this lower pressure drops, as can happen, for example, when the accumulator line 44, 26 becomes leaky, the Spring 36 the sleeve 37 and the piston 172 to the left, whereby it pulls the connecting rod 33 and the yoke 34 along in order to actuate the trailer brakes mechanically via the brake wires 35. Nevertheless, there is normally enough hydraulic energy stored in the accumulator to last in the event of a pump failure Apply the brakes hydraulically a few more times before applying the brakes mechanically. The number of these remaining hydraulic actuation depends on the size of the accumulator.

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A lever 161 (Pig. 1) is on the body 70 of the metering valve 160 articulated and acts on a rod .162 which engages the piston 72. With the lever 161 the trailer brakes operated independently of the brakes of the towing vehicle.

The dimensions of the hydraulic accumulator 170 (Pig. 2), as well as the force of its spring 36 and the initial pressure of the gas cushion in the chamber 176 are selected so that the smallest pressure required to overcome the spring 36 in the storage chamber is approximately equal to the initial pressure in the chamber 176 at which the piston 177 rests against the stop 179. Through this At the beginning of the filling process of the memory 170 via the line 26, the trailer tears are initially driven by the force the spring 36 is relieved before the piston 177 begins to move to the left.

Although the mechanical actuator and the hydraulic actuators are on one and the same Brake are shown acting, it may be appropriate to have separate brakes or at least separate brake shoes or -cushion for actuation by the hydraulic actuation mechanism. directions and to be provided by the multi-purpose memory.

A safety valve device 100 is in the trailer lines 26 and 28 switched on. This valve device has a housing 101 with channels 102 and 103, which the lines Connect 26 and 28 to the coupling heads 27 and 29. The housing 101 has a central longitudinal bore 104 in which sliding 3in. Piston 105 is added. One cross hole each 108 and 109 open into a channel 102 and 103, respectively. The inner ends of the transverse bores 108 and 109 taper conically to Form valve seat for balls (not shown) passing through Springs are biased against the conical seats. The conically tapered inner ends of the bores 108 and 109 open into the longitudinal bore 104 'and the balls protrude into this bore

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when they are against their seat. The piston 105 has a flat annular groove (not shown) that is usually level with the balls so that they are on theirs Being able to sit and rest. When the piston 105 is advanced in a manner to be described, the balls 111 rise from their seats and connect the channels 102 and 103 via the transverse bores 108 and 109 and a ring nut 113 in the piston 105.

The front free end of the piston 105 is fastened by means of a chain 180 to a block 121 which is fastened to the towing vehicle is.

The coupling heads 27, 29, 46 and 65 are thawed in the usual way and can be separated from one another by a strong pull without being damaged if the trailer suddenly accidentally releases from the towing vehicle. Every coupling head is provided with a self-closing valve, the movable valve closing body 127 or 128, the through Cooperation with the valve closing body 128 or 127 de3 corresponding head is held in its open position when the heads 27 and 29 with the corresponding heads 46 and 65 are coupled and automatically closed by springs when the coupling heads are separated from each other.

When the trailer becomes detached from the towing vehicle, the coupling heads 27 and 29 are separated from the heads 46 and 65. If the heads are separated _s press the valve springs, the valve closing body 127 and 128 against their seats in the respective coupling heads to the coupling heads to conclude, "At the same time the tractor pulls the piston 105, and this will open the ball valve to the storage line 26 to the brake line 28 to connect. The hydraulic accumulator 170 thereby automatically actuates the brake actuation devices 21 and 22 when the trailer is torn off. Eventually the chain 180 breaks to completely separate the piston - 15 -

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- 15 to effect 105 from the block 121.

Lines 26 and 28 or lines 44 and 64 usually comprise a flexible section of tubing. If the line 26 or 44 and in particular their flexible Hose sections are destroyed, an immediate pressure drop in the pressure accumulator 170 is the consequence, from which shows that the spring 36 actuates the trailer brakes mechanically, so that the driver is notified of the break. However, if the line 28 or 64 is broken, will the driver will only bark when the brakes are applied. However, if he applies the brakes and pressure is built up in the control chamber 73 of the metering valve, prevents Line break the building up of a corresponding pressure in the brake pressure chamber 76. As a result, the closing body 32 fully opened and the pressure fluid of the hydraulic accumulator flows out directly through the break point. Of the The resulting pressure loss in the accumulator causes the spring 36 to mechanically actuate the trailer brakes.

3 and 4 show another embodiment of a trailer braking system. In these figures, the same parts as in FIGS. 1 and 2 are provided with the same reference numerals and are not described again. . 1, FIG mainly characterized in that the metering valve 60 is not provided with a device 161, 162 for independently actuating the trailer brake of the towing ^vehicle: Figure 3 differs.. For the sake of simplicity, the closing bodies of the coupling heads 27, 29, 46 and 65 are not shown in FIG. 3.

The memory 20 shown in Fig. 4 differs from the memory 170 of FIG. 2 in that a cylindrical HohrQ / um 40 in the stationary housing 30 of the Storage 20 is divided into chambers 41 and 42 by a floating piston 43, the left chamber 41 with the

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Line 26 is connected and serves to store the pressurized fluids, while the right ISamer 42 is filled with a gas under an appropriate pressure in order to form a gas cushion. Thus, a piston 31 ', which is slidably received in the right end of the housing 31 and acts on the piston rod 32 and whose path is limited by the sleeve 37, is exposed to the gas pressure instead of the accumulator pressure. The gas cushion can be replaced by a spring which ^{acts between the piston 43 and} the piston 31.

The memory 20 is shown filled in FIG. 4. In the unfilled position, however, is the Piston 31 * in its left end position and piston 43 in its right end position. If the pressure of the liquid exceeds the pressure that the gas cushion in the Chamber 42 is initially exposed, the piston 43 moves to the right until there is equilibrium between the Pressures in chambers 41 and 42 adjusts. When the chamber 41 enlarges, the gas cushion is compressed further, and when the compressive force generated thereby on the piston 31 becomes as great as the biasing force in the spring 36, the piston 31 is thus moved to the right, whereby it releases the trailer brakes from the mechanically applied actuating force.

The operation of the brake system according to FIGS. 3 and 4 is essentially the same as that of the brake system according to FIGS. 1 and 2.

When so much pressure fluid has flowed out of the storage chamber 41 that the effect in the chamber 56 (FIG. 3) Pressure a £ has dropped to a value at which the spring 50 closes the closing body 49 of the relief valve 18

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can, the memory 20 is refilled by the pump 10. Usually that lower pressure is still there higher than the minimum pressure at which the accumulator spring 36 is fully compressed, as in Pig. is shown, wherein the FlarFch 94 of the piston 31 is supported on the housing 30 and the trailer brakes .completely of the mechanically applied actuating force are relieved. However, should the pressure in the accumulator drop to a value below this lower value, for example as a result of a Leaks in the storage line 44, 26 can happen, the spring 36 pushes the sleeve 37 and the piston 31 to the left, whereby the trailer brakes are operated mechanically. in the Initial state when the storage tank is completely empty, dJi. at in. piston 43 remaining at its left limit position, the gas pressure acting on piston 31 in chamber 42 is too low, to overcome the bias of the spring 36. If the Chamber 41 et \, a is filled up to a third of its full volume! has the pressure risen enough, to overcome the spring force 36 and completely the trailer brakes to free from the mechanically applied braking force.

Alternatively, the force in the spring 50 of the relief valve 18 (Fig. 3) and the dimensions of the hydraulic accumulator 20 (Fig. 4) including the characteristic its spring 36 as well as the initial force of the gas cushion in the chamber 42 with respect to the amount of pressure fluid that is released from the actuating devices 21 and 22 is required for a single actuation of the Breüffi by means of the master cylinder, be chosen so that the pressure in the memory drops below that pressure at which the spring 36 the piston 31 after starts moving to the left in order to apply the brake mechanically. In this way, the trailer brakes can be operated mechanically and hydraulically at the same time.

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The embodiment of the trailer braking system according to Figures 5 and 6 are similar in many respects to that of Figures 1 and 2. Like parts have been given like reference numerals provided and not described again.

In particular, the pump 10 for feeding the hydraulic devices of the towing vehicle 11, 12 is the relief valve 18, the metering valve 160 and the trailer brakes 21 to 2 * J-, 33 to 39 formed the same.

However, it is a hydraulic accumulator 151 (Fig. 5) arranged for the normal actuation of the trailer brakes on the towing vehicle. A multi-purpose storage device arranged on the trailer 140 (Fig. 6) forms a source for a hydraulic Pressure medium for emergency actuation of the trailer brakes and enables the trailer brakes to be actuated mechanically Pressure drop in the accumulator. This part of the braking system (Fig. 6) and the trailer is with the part of the braking system (Fig. 5) of the towing vehicle by means of a self-sealing Quick release breakaway coupling 1 * 4-1 connected. The brake line 28 leads from the trailer coupling head 29 to the hydraulic actuators 21 and 22, and a storage line 1Λ2 leads from the brake line 28 to the one arranged on the trailer Memory 1 * 4-0.

The hydraulic accumulator l40 (Fig. 6) comprises a stationary housing l * + 3 in which a piston 14 * 4- slides. The rod 1 * 4-5 of the piston I * l4 is coupled to the connecting rod 33 leading to the trailer brakes. A compression spring 1 * 4-6 acts between the housing 1 * 1-3 and the piston 1 * J4. The spring 1 ** 6 pushes the piston 1 * 44 to the left in order to actuate the trailer brake mechanically. It is sufficiently _s biased to effect complete operation of trailer brakes. The storage housing 1 * 4-3 has a cylindrical cavity 1 * 1-7, which is divided by the piston 1 * 44 into two chambers 1 * 1-8 and

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and 149 is divided. The length 148 is used for storage of hydraulic pressure medium and is in connection with the line 142 via a check valve 150. The Chamber 149 picks up the spring I46 and is in contact with the atmosphere. A gas cushion in the chamber 149 can supplement or replace the action of the spring 146.

The arranged on the towing vehicle memory 151 (Fig. 5) comprises a housing 152 which has a cylindrical cavity

153 on v / eist. The cavity 153 is divided into two chambers 154 and 155 by a floating piston 156. The chamber

154 dimt for storing hydraulic pressure medium while chamber 155 at an appropriate pressure Gas is filled to form a gas cushion. The gas cushion can be supplemented or replaced by a compression spring between the piston I56 and the end wall 157 of the Housing 152 acts.

The storage chamber 154 is filled via the relief valve 18 and a line 158 leading from the outlet opening 45 of the relief valve 18 leads to the chamber 154.

The relief valve 18 enables the pump 10, which is, for example, a gear pump and normally a constant one Delivery rate at variable delivery pressure supplies the storage chamber I48 and 154 to a predetermined pressure to fill up.

Initially, when the pump 10 begins to operate, and assuming that none of the hydraulic devices of the towing vehicle is working, i.e. all valves are in their open middle position or /. Are in the neutral position, flows the liquid conveyed by the pump via the non-return valve 55 through the memory line 158 to the memory

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Chamber 154. The attic 151 is in Pig. 5 in its partial padded position shown; however, the piston 156 is initially in its left end position. if the pressure of the liquid exceeds the initial pressure of the gas cushion in the chamber 155, the moves Piston 156 to the right until the pressures in chambers 154 and 155 are equal. When the memory pressure is at its reached by the spring 50 and the pressure in the chamber 53 predetermined value, the closing body 49 is after moved to the left, thereby opening the valve to

.To connect opening 19 to the discharge opening 47 /, which is below the pressure of the container 15 is.

When the trailer is attached to the towing vehicle, the memory 140 (Fig. 6) is initially empty, so that the Trailer brakes are mechanically operated by the spring 146. The memory is activated by the pump 10 by pressing the Metering valve 160 (Pig. 5) filled up, this valve between the inlet port 61 and the Breras outlet port • is kept completely open. The chamber 148 can thereby to a predetermined relief valve 18 by dao Pressure can be filled in exactly the same way as the chamber 154 of the accumulator 151 arranged on the towing vehicle. That The metering valve 160 can be kept open either by fully operating the pull-in brake lawns or by operating the lever 161.

The check valve 150 (Pig. 6) is preferably arranged on the housing 142 of the accumulator 140 and comprises one Closing body 163, which is normally pressed against the seat 164 by the pressure of the pressure medium in the chamber 148 is held. A spring (not shown) can also act on the closing body 163 in the same direction. A Cam 165 is mounted in an arm 166 of the housing 142

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and acts on the end of a valve rod 167 which passes through the valve seat 164 protrudes from the closing body 163. One end of a cord or chain 16b is with the end of one Lever 169 connected, which in turn is connected to the cam 165. The other end of the string or chain is attached to the towing vehicle or fastened in some other way.

The coupling heads 29 and 65 of the self-sealing ' Quick release breakaway coupling 141 include check valves, the closing body 127 and 128 of which against their seats Closing springs 129 are biased. When the head 29 is coupled to the head 65, the closing bodies are supported and 128 from each other so that the check valves are kept open.

When the trailer vehicle is torn off, the coupling heads 29 and 65 are separated and their check valves close themselves. At the same time, the tensile force in the sciinur or the chain 168, the check valve 163 is opened to relieve the pressure in the accumulator I40 the actuating devices 21 and 22 feed, so that the trailer brakes mechanically be operated.

Normally, before the trailer is unhitched from the towing vehicle, the lever 169 is operated to open the check valve 150 to open and the hydraulic fluid over the still coupled Clutch 141 and the non-actuated metering valve 160 to allow tin container 15 to flow off. This pushes 'the spring I46 the connecting rod 33 and thus the yoke 34 to the left in FIG. 6 in order to mechanically actuate the trailer brakes by means of the brake wires 35.

If desired, the accumulator 151 arranged on the towing vehicle can be used as a pressure medium source for the actuation

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the towing vehicle brakes are used. In this case are the actuation devices for the towing vehicle brakes are connected to the brake line 64 coming from the metering valve. The brakes can then be applied by operating the lever 161, v / obei the control chamber 73 and the Control opening 68 not applicable.

If the towing vehicle is equipped with a hydraulic system of the type with constant pressure, v / obei die hydraulic devices of the towing vehicle by means of valves controlled with so-called "closed means" verden and the pump is relieved via a pressure control valve, when all control valves are closed, that can The relief valve 18 is omitted and the pump 10 can be connected directly to the line 44 (Pig.l and 3) or 158 (Fig. 5).

. In comparison to the systems according to FIGS. 1 to 4, the system according to I ¹ Xg. 5 and 6 have the advantages that there is only a single pair of coupling heads and that the coupling heads do not necessarily have to hold the pressure during coupling or uncoupling (except when the trailer is torn off). However, this system has the disadvantage that the trailer brakes are not automatically actuated in the event of a line break in brake line 64 »28.

In another embodiment of the invention, jst an idt the pump 10, the memory 151 and the metering valve 160 equipped .Vehicle not provided with a coupling head 65 »but instead with a brake line 64 which directly is connected to the brake actuators.

Claims

9098 38/1083

Claims (16)

Claims 1., Hydraulic brake system with a memory as a pressure medium source, especially for power-operated Brakes, characterized by a relief valve (16) through which the accumulator (170; 20; 140) by means of a hydraulic pump (10), in particular a pump with a constant delivery rate, to a predetermined one l3uck can be filled and via which the pump line (14) is freely connectable to the reflux (15) so that the pump operates without back pressure when the predetermined pressure is reached. 2. Brake system according to claim 1, characterized in that the relief valve (18) is connected in series with at least one control valve (12) of the type with "open center position", as connected upstream of hydraulic modules (11). ' ^: 3. Brake system according to Claim 2, characterized in that it is rinz eich net that the relief valve (18) to the return flow (47) opens at a higher pressure than that at which it closes towards reflux. 4. Brake system according to claim 3, characterized in that the relief valve (18) comprises a valve closing body (49) which is movable against a valve spring (50) to a valve seat (51) between one with the inlet opening (19) in communication Inlet chamber (53) and an outlet chamber (57) connected to the ßückflußöffmmg (47), and that the valve closing 9Q9 & 3S / 1O8 3 19048U body (59) is attached to a piston (52) of larger diameter than the valve seat (51), the piston with one end face the pressure in the inlet chamber (53) and the other end face the pressure in a pressure chamber (56) is exposed, which is in communication with the pressure outlet port (45), with which the inlet port (19) is connected via a check valve (55). 5. Brake system according to one of claims 1 to 4> thereby characterized in that the memory (170: 140) is designed as a multi-purpose ^ eicher, which is used as a pressure medium source for the hydraulic actuation of the brakes at least in an emergency and also for the mechanical actuation of the Braking is used when a pressure drop occurs. 6. Brake system according to claim 5, characterized in that that the hydraulic actuators (21, 22) and the multipurpose memory (170; 20; 140) the same braking mechanism (24) act. 7. Brake system according to one of claims 1 to 6, dadurc h characterized in that the hydraulic actuators (21, 22) arranged on a trailer vehicle and with a metering valve provided on a towing vehicle (160; 60) via coupling heads (29, 65) which interact with one another between the towing vehicle and the trailer vehicle can be connected, the metering valve serving to connect the hydraulic accumulator (170; 20; I40) to the hydraulic To connect actuating devices. 8. Brake system according to claim 7, characterized in that that the memory arranged on the trailer vehicle (170; 20) via a second pair of interacting coupling heads (27, 46) with the outlet opening (45) of the relief valve (18) and the inlet opening (61) of the metering valve (160; 60) is connected (Fig. 1 to 4). 909836/108 3 9. Brake system according to claim 8, characterized in that that at least the coupling heads (27 and 29) provided on the trailer, locking elements (127) on v / iron, which automatically seal the coupling heads when they be separated from each other, and that one is attached to the trailer provided safety valve arrangement (100) the storage line (26) and the brake line (2b) when the Trailer connects with each other. 10. Brake system according to one of claims 5 to 9 »thereby characterized in that the multipurpose reservoir (170; 20) comprises a floating piston (177; 43) which a cylindrical cavity (174) in a stationary housing (171; 30) in a pressure chamber (175; 41) and a chamber Q-76; 42) divided into a spring, preferably a gas cushion, is arranged, and that a second piston (172; 31) is provided which the pressure in one of these chambers (175-, 176 or 41, 42) exposed to M and serves to relieve the brakes of the force of the spring (36) (Figures 1 to 4). • 11. Brake system according to claim 10, characterized in that that the pressure at which the relief valve compared to the. Reflux closes, is higher than the pressure, which is required to move the spring (36) against the 'stroke limiter (stop 94) of the second piston (172; 31) to press. 12. Brake system according to claim 10 or 11, characterized in that that the pressure at which the relief valve (18) closes with respect to the reflux is higher is than the! »minimum pressure that is required to achieve the moving the floating piston (177) away from its stop (179) (Figs. 1 and 2). 13. Brake system according to claim 5, characterized in that that the general purpose memory (140) with the 90 9 8 367108 3 _ M. - Brake line (28) via a safety valve, preferably a check valve (I50) is connected, which can be opened in an emergency by means of a lever (169) (Fig. 5 and 6). 14. Brake system according to claim 13, characterized in that that the hydraulic actuators (21, 22) and the multipurpose memory (140) on one Trailer vehicle are arranged and nets between the Coupling heads (29 and 65) provided for the towing vehicle and the trailer to a metering valve arranged on the towing vehicle (160) can be connected, with the metering valve (160) in addition serves to connect a hydraulic accumulator (151) provided on the towing vehicle to the brake line (64, 28) (Figures 5 and 6). 15. Brake system according to one of claims 1 to I4, characterized characterized in that the hydraulic accumulator (170; 20: 140) with the brake actuation TO? - directions (21, 22) connecting the metering valve (160; 60) has a piston (74) which in one direction by the in a control chamber (73) prevailing control pressure and in the other direction by the one with the actuating devices connected pressure chamber (76) prevailing brake pressure movable it. 16. Brake system according to claim 15, characterized in that g e k e η η-draw t that the metering valve (160; 60) comprises a valve closing body (82) with a stationary between the. inlet chamber (80) and the pressure chamber (76) arranged Valve seat (79) as well as with a second valve seat (bl) provided on the piston (74) interacts, the second The valve seat (bl) is connected to the return flow at least when it is at a distance from the valve closing body (82) 909836/1083 and thereby with the pressure chamber (76) in connection
stands, and where .the piston. (74). is moved by the pressure in the control chamber (73) until the second seat (81) engages the closing body (82) and then the closing body (82) is lifted from the stationary seat (79). 909836/1083